Synthesis Of Core-shell Structured SiO₂@Au Nanoparticles

SiO2@Au has excellent performance including infrared extinction, linear optical, and photothermal conversion. Self assembly-electroless plating, the most common method of synthesizing SiO2@Au, has advantages, such as high coating rate, uniform surface morphology, good sample stability and high controllability. But there are still many problems, including the complicate and tedious process, which inhibited the application. In this thesis, SiO2@Au was successfully prepared through SAM-electroless plating. The effect of the volume ratio of K-Gold solution and gold-seeded silica sol on the properties of SiO2@Au samples was investigated, and the optimum value of the volume ratio was determined. In addition, the synthesis of SiO2@Au through self assembly-electrostatic adsorption was carried out, and comparative studies were carried on the characteristics of morphologies and optical absorption properties of the SiO2@Au synthesized by both SAM-electroless plating and SAM-electrostatic adsorption. The main results are listed as follows:(1) Silica microspheres about200nm were prepared through improved Stober method, then were functionalized by APTMS. The effects of reflow parameters on the attachment of APTMS on silica were investigated, and the optimized process parameters were obtained. Gold nanoparticles about1-3nm were selected as gold seeds and successfully attached to the APTMS-functionalized silica.(2) The core-shell nanoparticles of SiO2@Au was successfully obtained by SAM-electroless plating, the effects of the volume ratio of K-Gold solution and gold-seeded silica sol on the synthesis of SiO2@Au samples were studied, the optimum value of the volume ratio was determined.(3) The core-shell structured SiO2@Au nanoparticles were synthesized through SAM-electrostatic adsorption for the first time, and comparative studies were carried on the characteristics of morphologies and optical absorption properties of the SiO2@Au synthesized by both SAM-electroless plating and SAM-electrostatic adsorption. The experimental results indicated that the shell integrity and uniformity of SiO2@Au synthesized by SAM-electroless plating is better, but requires more steps and longer reaction time, while the SAM-electrostatic adsorption process is relatively simple.